Calibration of modeling

gtinkler · Posts: 5

I am trying to evaluate Designbuilder for RetroCx projects and wondered how easy it is to calibrate the model for existing buildings with known uitlity costs?

Andy Tindale · Posts: 1110 Location: Stroud

Dear Greg,

You can use DesignBuilder to calibrate a model against recorded data for existing buildings and we will be contributing to a UK government funded research project starting this year called CaRB to develop advanced stock modelling simulation capabilities. A significant part of this work is to calibrate the models used to represent the building stock and we will be developing new tools for DesignBuilder to assist with this process.

In previous projects I have worked on where calibration was required, the first task is to match internal gains in the model with recorded data. To assist with this we have a survey software utility to record every internal gain and item of electrical and other equipment in an existing building, categorised by end use type and zone. The data includes detailed information on hours of use for each day of the week, rated power, utilisation factor, connected meter etc.

The software utility allows you to sum energy consumption for each meter "bottom-up" and compare this with recorded meter energy consumption. The software allows you to calibrate the equipment energy consumption to ensure a match with the recorded meter energy consumption. The calibrated equipment data can then be exported in a form which can be imported into DesignBuilder. Because each item of equipment has a zone name the equipment can be correctly positioned in the appropriate DesignBuilder zone.

To do this you must use the DesignBuilder "detailed" gains model option where each item of equipment is defined. This option was originally developed to handle data from the survey software utility.

The other major areas for calibration are of course heating and cooling which cannot so easily be adjusted to give a match with recorded energy consumption data. This tends to be much more of a "trial and error" process. In previous projects we have tended to assess which is the data with the highest uncertainty in the model and adjusted this to give agreement with recorded heating and cooling energy. There is no software methodology implemented to do this yet, though we have implemented heating and cooling energy calibration tools in a previous project for the UK 3TC/NDEEM stock modelling application and expect to reproduce these in the DesignBuilder stock modelling toolset.

The survey software utility is not yet commercially available, though if you were keen we could probably give you a trial.

In answer to your question about how easy it is to calibrate DesignBuilder models, I would say that model calibration is never "easy" and generally requires some specialist knowledge (and patience). However we do have a proven methodology which we would be happy to share.

I hope this helps - please let me know if you would like to pursue this.

Regards
Andy

gtinkler · Posts: 5

Yes I would. I like the 3 dimensional modeling aspects of your GUI. I am currently using TRACE. I see an introductory course being offered at MIT here in the states soon. Any other state side courses that you are aware of? What would you like from us?

Andy Tindale · Posts: 1110 Location: Stroud

Regarding DesignBuilder training in the States, I don't think there are any other courses planned (apart from the one on July 31 at MIT), but you should contact Charlie and his team at www.DesignBuilderSoftware.com for more information about future DesignBuilder training events.

It would be useful if you could give me more information about your requirements for building calibration to be sure that we can provide the tools to meet your needs. In the meantime we will prepare a test package of the Survey software tool for you to try.

Regards
Andy

gtinkler · Posts: 5

We are a Mechanical, Electrical and Plumbing Consulting Engineering firm. I am involved in Retro-Commissioning of all types of buildings from Department stores to office buildings to 75 story high rise office buildings. We get utility meter data from the Utilty companies and plans from building owner and then model and calibrate to those parameters. Further metering might be done if I had software that would accept the data or the data had some point of calibration within the software. Right now the modeling software I use only prints out "total building" useage by fuel and so with utility bills I attempt to calibrate to that; with pretty good results so far but I have used this package now for 10 years and gotten comfortable with it. Several of the utility companies over here offer "payments" to the building users for these services as part of their Demand-side management program. The reports that come out of the modeling need to be understood and methodoly shown. I am thinking with yours using the "energy plus" base and that this is available for free from USDOE and that the overseers of these programs can aquire "energy plus" for free; that makes it attractive for the review process. What do you think?

gtinkler · Posts: 5

I would also like to use if for geothermal loopfield designs and would need load profiles by month in both diversified peak and cumulitive volumetric heat by month in order to accomplish this. Is this an output of DesignBuilder/Energy Plus?

Andy Tindale · Posts: 1110 Location: Stroud

Greg,

My apologies for the slow response.

Yes DesignBuilder/EnergyPlus can generate load profiles such as the ones you describe, though you would need to do some processing to generate cumulative volumetric heat data.

Also, although DesignBuilder does not yet directly support this, you could use DesignBuilder to generate EnergyPlus data sets and model ground source heat pumps directly in EnergyPlus.

Andy

Andy Tindale · Posts: 1110 Location: Stroud

Your idea of using EnergyPlus as the calculation engine for calibrated building models is entirely feasible. One advantage of using a more advanced calculation method is that you can check that the internal temperatures in the model correspond approximately with those recorded in reality and because you get pretty good control of the model you can tweak it until it agrees with recorded data.

The calibrated model then provides an excellent tool for demand side management, investigating the effectiveness of various energy saving measures etc.

The process you describe corresponds closely with projects we have carried out in the past.

We also have tools to allow real weather data to be adjusted to agree with recorded degree days close to the site (since hourly weather data is rarely available for specific periods/locations)

EnergyPlus is increasingly trusted as a calculation method and, as you say, this would make it attractive for the review process.

I would like to offer you a trial of the combined DesignBuilder/survey data collection software. This package is not yet a polished commercial product, but the underlying methodology has been used extensively as part of the NDEEM project and the specific DesignBuilder implementation has been tested on six buildings in the UK with survey data provided by non expert contractors and analysis within DesignBuilder by simulation experts.

Regards

Andy

gtinkler · Posts: 5

How long would the trial period be and what is the fees after the trial period is over? I need to spend some time with Design Builder as it is new to me and I am more comfortable with other modeling softwares.

Andy Tindale · Posts: 1110 Location: Stroud

The standard DesignBuilder evaluation period is 30 days, but if this is not enough we would be happy to extend. During this period you would also have free use of the Survey/Calibration software tool.

If, having tested the software, you wish to proceed, you will need to purchase a license to use DesignBuilder ($1449). In this case, we will give you free use of the Survey/Calibration software utility on the understanding that the software is not yet commercial quality and that you would help us by providing feedback to help us to fix any problems.

The survey/calibration tool comes with example files and a help document. We will provide backup support and guidance should this be required.

Regards
Andy

Andy Tindale · Posts: 1110 Location: Stroud

The Survey Data Collection and Calibration tool is now available from the Downloads page under Prerelease and betatest. Documentation is provided. The software is still in Alpha test mode and we expect to make usability improvements later in the year, possibly integrating the software within DesignBuilder.

An example data set is available on the Data section of the Downloads page.

Andy

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